“ The PCs are sent with a diplomat to another country to protect him and do his bidding. There may be some espionage, rescuing, downright bullying, etc. Could make a nice medieval, special operations background.”
“ If you want to add a 'supernatural' touch to your campaign, define the rules of magic and the universe. Make your players comfortable with those rules. Then your new supernatural creatures must then break those rules.”
“ A plague is spreading trough the lands, the plague is actually an old woman carrying a stick. She walks from farm to farm spreading the plague. Can the PCs stop her without getting infected.”